STEAM UNDER PRESSURE.—Which is hotter,—the "steam" (i.e. water vapor) coming from boiling water in an uncovered saucepan or teakettle or the "steam" which has been held underneath the lid of a covered saucepan or teakettle (see Figure 32)? Steam confined in a small space or held under pressure may reach a temperature higher than that of boiling water.

EFFECT OF HIGH TEMPERATURE UPON POP CORN AND POTATOES.—Pop corn contains water. When heated, the water changes to steam. The covering of cellulose holds the steam in the kernel. When the steam expands and reaches a temperature far above the boiling point of water, it finally bursts the covering and the starch swells at once.

[Illustration: FIGURE 32.—"STEAM" WITHOUT PRESSURE AND "STEAM" WHICH HAS
BEEN UNDER PRESSURE.]

In baking potatoes, the water contained in them vaporizes. The vaporized water or steam is held under pressure by the skin of the vegetable. The steam thus becomes hotter than boiling water, hence a baked potato is cooked at a higher temperature than a boiled potato, and no nutrients are lost.

POP CORN

Moisten pop corn with cold water. Almost cover the bottom of a popper with the kernels. Hold the popper first at some distance from the heat and then gradually bring it closer, shaking it well all the time to keep the corn from burning. The corn should not begin to pop before three and one half minutes. When popping commences, most of the kernels should open. If there is some time between the popping of the first and last kernels, the corn will become tough.

BUTTERED POP CORN NO. I

4 quarts freshly popped corn 1/4 cupful butter Salt

Melt the butter and pour it over the corn, stirring with a spoon. Sprinkle at once with salt from a salt shaker, continue stirring.

BUTTERED POP CORN NO. II

1 tablespoonful butter and 1 tablespoonful oil or 2 tablespoonfuls oil 1/2 cupful shelled pop corn Salt

Put the fat in a large frying pan; when melted, add the salted corn. Stir until the corn is evenly coated with fat. Cover closely and heat gradually, shaking the pan vigorously all the time.

BAKED POTATOES Scrub potatoes and place them on the grate of a hot oven (500 degrees F.). (Potatoes should be baked in a hot oven, to prevent them from becoming waxy or soggy.) Bake until soft when tested with a fork or knitting needle, usually 50 to 60 minutes. Break the skin at once to allow the steam to escape, or make two gashes in the top of each potato, one at right angles to the other. Gently press the potato so that the steam may escape. Serve in an uncovered dish. Place the steaming potatoes on a folded napkin for serving.

STUFFED POTATOES

2 tablespoonfuls butter or substitute 1 teaspoonful salt 3 tablespoonfuls milk Pepper 6 baked potatoes

Cut the baked potatoes in halves lengthwise. Remove the inside, taking care not to break the skin; mash the potatoes, add the milk, butter, and seasoning, and beat them as ordinary mashed potatoes. Return the mixture to the potato shells, place the stuffed potatoes in a pan, and bake in a hot oven (500 degrees F.) until brown.

Before browning the stuffed potatoes, grated cheese may be sprinkled over them.

QUESTIONS

Explain why pop corn can be cooked thoroughly in about 5 minutes while rolled oats or wheat requires 1 1/2 hours for sufficient cooking.

Analyze the difference in taste of a baked and a boiled potato. To what is the sweet taste of a baked potato due (see Experiment 26)? Explain fully why baked potatoes are more easily digested than boiled potatoes (see Experiment 26 and Solution and Digestion).

Which contains more nutriment,—baked potatoes or boiled potatoes? Explain (see Comparison of Vegetables Cooked with and without the Skins, and in Water or in Steam).

What is the purpose of breaking the skins of potatoes at once after baking? Why are baked potatoes served in an uncovered dish? What could be used to cover them?